Polyazolyl Chelate Chemistry. 3. (σ-Organyl)(tris(pyrazol-1-yl)borato)ruthenium Complexes

Abstract

The reactions of K[HB(pz)3] (pz = pyrazol-l-yl) with the coordinatively unsaturated a-vinyl complexes [Ru(CR=CHR)Cl(CO)(PPh3)2] (R = H, Me, C6H5) proceed with loss of a chloride and a phosphine ligand to provide the compounds [Ru(CR=CHR)(CO)(PPh3)(HB(pz)3j] in high yield. Similar treatment of the complex [Ru(C6H4Me-4)Cl(CO)(PPh3)2] leads to the related σ-aryl derivative [Ru(C6H4Me-4)(CO)-(PPh3)(HB(pz)3)]. The α-(phenylethynyl)-trans-β-styryl complex [RuC(C=CPh)=CHPh}(CO)(PPh3)-{HB(pz)3}] is obtained in high yield via the successive treatment of [RuClH(CO)(PPh3)3] with 1,4-di-phenyl-l,3-butadiyne and K[HB(pz)3]. The molecular structure of [Ru{C(C≡CPh)≡CHPh}(CO)-(PPh3){HB(pz)3}], determined by X-ray diffraction, can be described as pseudooctahedral with two enantiomeric forms in the asymmetric unit. The vinyl ligand is almost coplanar with the carbonyl ligand aligned in such a way as to maximize π-retrodative interactions.